The present disclosure relates to electro-optical sensors, to sensor kits and methods for detecting an analyte in a sample.
The analysis of bimolecular interactions plays an important role in medical applications for disease progression, prognosis and prevention. Specific biomolecule interactions (e.g. induced fit) can be used in healthcare (biosensors, biochips, lab-on-a-chip) and lifestyle applications (mood sensors) or for sensing environmental changes (ecological sensors) or as military devices (sensors for biological weapons and warfare agents).
In all these cases, a miniaturization of the device in combination with a multiplexing capacity and simple sample handling for small sample volumes is needed and summed up under the keywords “point-of-care” and “point-of need” application. Another desirable feature of, e.g., biochips is fast and reliable sample readout. Most applications reported or developed in this area are based on either optical readout with fluorescence (e.g. microarrays) or electrochemical readout (e.g. blood-glucose tests), both comprising several advantages and disadvantages.
One of the first biosensors for medical application was published in 1962, dealing with the development of a glucose sensor based on glucose oxidase [1]. Nowadays, chip-based detection methods for medical diagnosis are still of special interest in an emerging research field [2]. In general, biosensors consist of three relevant elements: a bio-molecular recognition element, a signal transducer and the signal readout system. They are based on substrates like glass, polymers, cellulose membranes to name but a few. As bio-molecular recognition element, enzymes [3], DNA [4], cells [5] and antibodies [6] may be used. The signal can be transduced by mechanical means, by optical means or by electrical means. Dependent on the transducer, several readout methods for bio-sensing devices are known and published. Among them are optical sensors [7] (e.g. fluorescence, luminescence and plasmonics), electrochemical sensors [7], [8] (e.g. amperometric and potentiometric sensors), magnetic bead sensors [9] and piezoelectric sensors [10]. Silver enhancement may be used for electrical readout of the signal for DNA detection [11].